OTHER ASSETS - Summarized Financial Information, Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenues	$ 1,512	$ 1,539	$ 1,283	$ 1,609	$ 1,622	$ 1,125	$ 771	$ 722	$ 5,943	$ 4,240	$ 3,055
Operating (loss) income	625	$ (4,216)	$ 492	$ 327	277	$ (6)	$ 106	$ 93	(2,772)	470	660
Net income (loss)									(2,429)	105	346
Assets And Liabilities [Abstract]
Current assets	3,217				2,913				3,217	2,913
Current liabilities	1,034				1,134				1,034	1,134
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Income Statement [Abstract]
Revenues									611	386	145
Operating (loss) income									147	47	(58)
Net income (loss)									23	13	$ (82)
Assets And Liabilities [Abstract]
Current assets	493				369				493	369
Noncurrent assets	4,219				4,056				4,219	4,056
Current liabilities	410				118				410	118
Noncurrent liabilities	$ 2,327				$ 2,313				$ 2,327	$ 2,313